1. Field of the Invention
The present invention relates to a behavior monitoring system for a rotary body.
2. Description of the Related Art
In a mechanical seal for sealing a rotary shaft or so forth, it is quite important for monitoring behavior of a seal ring of a rotary shaft or a mechanical seal. In the mechanical seal, it is possible to predict occurrence of a leakage in the mechanical seal in advance by monitoring radial and/or axial displacement of the seal ring forming a sealing surface. A device for predicting such failure has already been proposed.
However, since the conventional device monitors behavior of the rotary body, such as the seal ring of the mechanical seal, both in the radial and axial directions, at least two displacement sensors have to be provided to cause high cost. Furthermore, mounting of two sensors requires careful consideration for determining the mounting positions as well as labor intensive mounting operation. In particular, in case of the mechanical seal, the displacement sensors are frequency mounted in a severe environment, such as high temperature, high pressure or corrosive fluid or so forth. For withstanding under such severe environment, relatively expensive sensor has to be employed so that the increasing of number of sensors to be installed creates substantial cost problem.